Projector and searchlight



Au 31, 1931. J. KIEFER 2,091,818

PROJECTOR AND SEARCHLIGH'!" Filed May 11, 1934 Inventor Joh armes' Klefer Ha 8, fiwiw Is Attorney Patented Aug. 31, 1937 UNITED STATES PATENT OFFICE PROJECTOR AND SEARCHLIGHT Application May 11, 1934, Serial No. 725,130

In Germany Claims.

My invention relates to projectors and searchlights having an electric are as the source of light, and more particularly to means for regulating the position of the are.

In high-powered projectors of the type above mentioned, it is desirable to maintain the positive crater at or near the focus of the mirror. Due to the irregular consumption of the electrode ma terial, a constantly operating feed mechanism does not accomplish this object and, therefore, various means have been devised for starting and stopping the feed mechanism in response to a change in the position of the crater. Such operation is unsatisfactory for the reason that the starting and stopping of the feed mechanism inherently introduces a lag in the regulation of the electrode and thereby causes an irregular operation of the projector.

It is an object of my invention to provide a continuous feed for the positive electrode to compensate for a predetermined average consumption thereof and to provide means independent of this continuous feed for regulating the consumption of the electrode and for maintaining the crater substantially constant at a predetermined position.

For a better understanding of my invention, together with other and further objects thereof, reference is had to the following description, taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the accompanying drawing Fig. 1 illustrates a portion of a projector arc lamp including the negative electrode and a portion of its holder, the positive electrode, together with its holder and continuous feed mechanism, and a sectional view of the consumption regulating means; and Fig. 2 is a perspective view of the electrode consumption regulating means.

Fig. 1 in the accompanying drawing illustrates the electrodes of an arc lamp commonly used for Searchlight purposes. The positive electrode 1 is mounted horizontally in a holder 2, and the negative electrode 3 in a holder 4 is mounted in front of the positive electrode and at an angle thereto so that the light from the positive electrode tip 5, commonly called the crater, can be projected upon a reflector surface 6.

During operation of the lamp, the positive electrode l is consumed at a rate which is not uniform but which may be averaged for any electrode whose composition and operating current are known. For a steady and continuous operation of the lamp an average rate is not satisfac- June 26, 1933 tory and some means must be provided to regu-- late the consumption of the electrode and thereby maintain the crater 5 at a predetermined position with relation to the mirror surface 5.

In accordance with my invention, I provide a continuously operated mechanism for advancing the electrode including feed rolls 1 and 8 which are pivoted on arms 9 and I0 and engage the positive carbon at opposite sides. The feed rolls are respectively attached to interlocking worm gears II and [2 which are in turn driven by a motor [3 through bevel gears l4 and I5, shaft is and worm IT. The motor is continuously energized during operation of the lamp and advances the positive carbon at a predetermined average rate which is equal to the predetermined average rate of consumption of the electrode at normal operation.

At the forward end of holder 2, I also provide a disc 28 which is preferably mounted in the face of the holder 2 so that its face is flush with the face of the holder. This disc 20 is illustrated in section in Fig. 1 and. a perspective view thereof is illustrated in Fig. 2. Any simple means, such as a set screw 2!, may be used to hold this disc in place and provide for quickly removing it when necessary to replace it by a new one. The disc 20 is provided with a tapered, or conical, opening 22 through which the carbon I projects. The taper of this hole 22 may be chosen to suit various rates of regulation and in my present form is indicated to be approximately The regulation obtained by this construction is due to the variable portion of the cooling surface which is presented to, or is contacted by the arc and the electrode or in other words, due to the variation of the distance between the arc and the conical surface in the disc more or less heat is conducted away from the arc, thereby retarding or enhancing correspondingly the consumption of the electrode. For normal operation the arc is maintained at a distance wherein the arc is influenced by only the outer edge of the disc. If the rate of consumption is below the average, the crater will be moved away from the disc whereby less heat is conducted away by the disc and consequently the temperature and consumption of the electrode are increased. If, on the other hand, the consumption of the electrode is higher than normal, the continuous feed is not sufficient to maintain the crater at the predetermined position and the crater moves nearer the disc. As this movement takes place the tapered, or conica1,' wall presents a gradually increasing cooling sur face area to the arc and thereby increasingly cools it to retard consumption and permit the crater to move forward in response to the continuous feed. The material of the disc 20 is preferably cast iron, but may be made of any other suitable material which will readily conduct heat from the electrode and the arc, and which will not be subject to rapid deterioration.

In operation the motor i3 is set at a speed which Will compensate for the predetermined average consumption of the electrode and thereby maintain the crater approximately in the proper position. The crater being maintained near the disc 26, as above explained, such disc conducts away a portion of the heat of the arc and of the electrode. If the consumption of the electrode is too slow the crater will be advanced by the motor and the arc will be moved away from the disc so that consequently less heat will be absorbed by the disc and the rate of consumption of the electrode will increase. If, on the other hand, the temperature of the electrode rises and the rate of consumption thereof is increased, the arc crater moves closer to the disc 26 which through its tapered walls presents a variable cooling surface to the arc and conducts away a greater portion of the heat of the are as it moves in this direction, thereby reducing the rate of consumption and permitting the arc crater to be advanced away from the disc until a proper heat balance is reached. This regulation is thereby superposed upon the continuous feed and provides a simple,inexpensive and yet accurate means for maintaining constant the position of the positive crater at the focal point of the mirror.

What I claim as new and desire to secure by Letters Patent of the United States, is:-

1. In a projector mechanism, the combination of an electrode, a holder for said electrode, means for continuously feeding said electrode through said holder at a rate equal to the average rate of consumption of said electrode, and an iron disc mounted in said holder presenting a concave heat absorbing surface to the operating end of said electrode for regulating the consumption of said electrode in response to movement of the end of said electrode relatively to said disc and for maintaining it constant at a predetermined position.

2. In a projector mechanism, the combination of a positive and a negative electrode, means for continuously and uniformly feeding said positive electrode, a holder therefor, and a heat-conducting disc provided with a conical opening concentric with said positive electrode secured in said holder adjacent the operating end of said electrode for regulating the heat conduction from said electrode end in response to axial movements of the said end of said electrode relatively to said disc.

3. In a projector mechanism, the combination of a positive and a negative electrode, means for continuously and uniformly feeding said positive electrode, a holder for said positive electrode, a heat-conducting disc detachably mounted upon said holder and provided with a conical opening through which said positive electrode projects, the operating end thereof and said disc being maintained in a variable heat exchanging relation for regulating the consumption of said electrode in response to a movement of said electrode end relatively to said disc and thereby maintaining constant the position of the crater at the end of said electrode.

4. In a searchlight mechanism, the combination of a positive and a negative electrode, a holder for said positive electrode, an iron disc provided with a conical opening concentric with said positive electrode attached to the arc end of said holder, means for feeding said electrode at a rate sulficient to compensate for the average consumption of said electrode and for maintaining the end of said electrode in a heat exchange relation with the conical surface of said openings in said disc which varies in proportion to the variations from the averagerate of consumption of said electrode to maintain constant th position of the end of said electrode.

5. In an arc lamp the combination of a positive carbon, a holder therefor comprising a metal body having a conduit for the passage of the said carbon through it and having a face substantially at right angles to the axis of said conduit, means for feeding said carbon through said conduit at a rate substantially equal to the average rate of consumption of said electrode, and means for regulating said consumption comprising a metal disc attached to the face of said holder and provided with a conical concave surface which absorbs heat during the consumption of said electrode, the amount of said absorption being inversely proportional to the variation of the distance between the end of said carbon and said conical surface.

J OHANNES KIEFER. 

